• 한국소음진동공학회논문집
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• 제18권4호
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• pp.439-447
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• 2008

One of the key elements in efforts to minimize noise radiation from a powertrain is the knowledge of the main radiating component and the relation between the surface vibration of a powertrain and the sound pressure. In this research, the powertrain model is developed based on FEM(finite element method). This model is applied to the prediction of the vibration of a powertrain by using ADAMS and the radiation noise by using BEM(boundary element method). According to this numerical analysis, the surface vibration of a powertrain is investigated as a source of radiated noise. This surface vibration is caused by the 1st order natural vibration of the cylinder block and its mode shape is the torsion mode. Therefore, this mode shape is modified to reduce the surface vibration of the powertrain. The radiation noise of the modified powertrain is also reduced to $5{\sim}12\;dB$. This modification is very successful for the noise reduction based on the CAE technology.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.719-722
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• 2002

This paper reports the characteristics of a bidirectional antenna by using a planar array of a probe excited circular ring. The element of a bidirectional antenna is first designed to achieve the maximum directivity. The directivity can be further increased by arranging these elements to form the linear array. There are two types of linear array to be investigated i.e., on axis and off axis arrangement. On-axis linear array yields better directivity than off-axis linear array. Therefore, this orientation is further used to form the planar array. The radiation characteristics of this optimum planar array are rigorously reported. The proposed structure is very useful to extend the distance between the base station in PCT system.

• 한국전자파학회논문지
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• 제23권4호
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• pp.441-448
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• 2012

본 논문에서는 소형 USB dongle에 적용을 위한 다중 대역 MIMO 안테나를 제안하였다. 제안된 MIMO 안테나는 변형된 미엔더 라인과 역 L형 스터브로 구성되어 있으며, 접지면을 기준으로 서로 대칭적으로 상 하단에 위치한다. 구현된 안테나는 LTE 13, 17 대역(704-787 MHz), DCS/PCS/WCDMA 대역(1.71-2.17 GHz), LTE 7 대역(2.5-2.7 GHz) 대역에서 VSWR 3:1을 만족하였다. 효율 특성은 전체 주파수 대역에서 평균 35 % 이상의 값을 갖고, 상관 계수는 LTE 13, 17 대역에서 0.45 이하, DCS/PCS/WCDMA 및 LTE 7 대역에서 0.1 이하의 값을 갖는다.

• 한국전자파학회논문지
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• 제12권7호
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• pp.1057-1066
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• 2001

본 논문에서는 전자기적으로 결합하는 다이폴을 이용하여 직선편파를 복사하는 마이크로스트립 안테나의 설계에 관하여 기술하였다. 다이폴의 위치에 의해 서로 다른 직선편파를 가지는 안테나의 해석 및 설계는 FDTD 법으로 행하였다. 급전선로와 복사소자간의 상호결합을 고려한 단일 소자 안테나의 설계로부터 각 편파에 대한 설계파라미터들을 구했으며, 이를 이용한 어레이 설계에서 Offset을 변화시켜 복사전력을 조절할 수 있었다. 또한 어레이 소자간의 간격을 조정함으로써 원하는 방향으로의 지향각을 설계할 수 있었다. 5 소자 어레이 안테나를 제작하여 측정을 행하였고, 이들 결과는 이론치와 잘 일치하였다.

• Journal of electromagnetic engineering and science
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• 제18권2호
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• pp.108-116
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• 2018

In this paper, a method of designing a Vivaldi type phased array antenna (PAA) which operates at S-band (2.8-3.3 GHz) is presented. The presented antenna uses broadside coupled split ring resonators (BC-SRRs) for high isolation, wide field of view, and good active S-parameter characteristics. As an example, we design a $1{\times}8$ array antenna with various BC-SRR structures using theory and EM simulations. The antenna is fabricated and measured to verify the design. With the BC-SRR implemented between the two radiating elements, the isolation is shown to be enhanced by 6 dB, up to 23 dB. The scan angle is shown to be within ${\pm}53^{\circ}$ based on a -10 dB active reflection coefficient. The operation of the scan angle is possible within ${\pm}60^{\circ}$ with a little larger reflection coefficient (-7 dB to -8 dB). The proposed design with BC-SRRs is expected to be useful for PAA applications.

• 한국정보통신학회논문지
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• 제5권4호
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• pp.822-828
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• 2001

본 논문에서는 구형 캐비티 부착형 고이득 마이크로스트립 안테나를 설계 및 제작하였다. 단일 마이크로스트립 패치는 기본적으로 이득이 낮다. 이득개선법에 따라 상층기판을 두는 기술이 캐비티 부착형 $2\times2$ 마이크로스트립 배열 안테나에 적용된다. 안테나를 설계함에 있어서 비록 캐비티가 커짐에 따라 이득이 증가하지만 캐비티 크기가 $3\times3$ 파장이면 충분하다. 방사 소자간의 길이는 1.5배의 자유공간 파장으로 한다. 안테나 방사특성은 IE3D 소프트웨어로 계산되고 측정치와 실험적으로 비교한다. 실험 결과는 최대 이득이 9.16GHz에서 18.6dBi의 이득을 가지고 이는 계산결과와 잘 일치한다.

• 한국군사과학기술학회지
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• 제17권1호
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• pp.57-63
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• 2014

In this paper, we have proposed a wide band antenna for manpack SDR(Software Defined Radio). The proposed antenna consists of feeding post, flexible gooseneck and two radiating elements composed of a upper and lower radiators. The upper radiator has a longer electrical length than the lower radiator in order to operate in the lower frequency. Also, the resonant frequency and impedance characteristics of the antenna can be adjusted independently for two radiators. Therefore, the proposed antenna can be achieved wide impedance bandwidth by the combination of two independent resonance modes. To analyze the characteristics of the antenna in the design process is employed the equivalent circuit theory and EM(Electro-Magnetic) simulation. The measurement results show that the proposed antenna have the sufficient wide bandwidth, above -3.4dBi of the gain and fairly good radiation pattern over the wide bandwidth.

• Journal of the Optical Society of Korea
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• 제8권4호
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• pp.174-181
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• 2004

Various kinds of systems, that can do target recognition and position detection simultaneously by using infrared sensing detectors, have been developed. In this paper, the detection system TRSS (Thermal target Recognition by Spiral Scanning) adopts linear array shaped uncooled IR detector and uses spiral type fast scanning method for relative position detection of target objects, which radiate an IR region wavelength spectrum. It can detect thermal energy radiating from a 9 m-size target object as far as 200 m distance. And the maximum field of a detector is fully filled with the same size of target object at the minimum approaching distance 50 m. We investigate two types of lens systems. One is a singlet lens and the other is a doublet lens system. Every system includes one aspheric surface and free positioned aperture stop. Many designs of F/1.5 system with ${\pm}5.2^{\circ}$ field at the Efl=20, 30 mm conditions for single element and double elements lens system respectively are compared in their resolution performance [MTF] according to the aspheric surface and stop position changing on their optimization process. Optimum design is established including mechanical boundary conditions and manufacturing considerations.

• International Journal of Internet, Broadcasting and Communication
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• 제16권1호
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• pp.330-338
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• 2024

In this paper, a Ka-band high-output active phased array antenna device applicable to small radars and seekers was designed, and the improved performance was studied. The radiation device assembly consists of 1x8 arrangements, and the step flared notch antenna type. It shows low active reflection loss characteristics in broadband, and low loss characteristics by applying the air-strip feeding structure, and is designed to enable beam steering up to 45 degrees. The TRM(transmit receive module) output power is more than 2.0W per channel using GaN HPA in the transmitting path, and satisfies more than 25.0 dB gain and less than 6.0 dB noise figure in the receiving path. Accordingly, the Effective Isotropically Radiated Power(EIRP) of the antenna unit shows the performance of 0.00 dB or more and the receive gain-to-noise temperature ratio(G/T) of 0.00 dB/k or more. For demonstration, we have designed aforementioned planar array antenna which consists of 64 radiating elements having a size within 130 mm x 130 mm x 300 mm and weight of less than 4.9 kg..

• 한국ITS학회 논문지
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• 제15권2호
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• pp.95-101
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• 2016

본 논문에서는 주차장관리 시스템 기지국용 소형 ${\lambda}/4$ 폴디드 마이크로스트립 안테나를 제안, 설계 및 제작하였다. 제안된 안테나를 소형화하기 위해 먼저 기준 ${\lambda}/2$ 마이크로스트립 패치 안테나에서 방사소자 폭을 줄이고, 다음은 방사소자 길이를 줄여주기 위하여 섭동효과(Perturbation effect)를 이용하여 개구면에 폴디드 구조를 적용하였다. 끝으로 ${\lambda}/2$ 길이의 폴디드 마이크로스트립 안테나를 ${\lambda}/4$ 폴디드 마이크로스트립 안테나로 더욱 소형화시켰다. 설계된 안테나는 중심주파수 425 MHz에서 크기는 $134mm{\times}143.85mm{\times}20.1mm$($0.19{\lambda}{\times}0.2{\lambda}{\times}0.028{\lambda}$, ${\lambda}$는 425 MHz의 한 파장 길이)로 기본 마이크로스트립 패치 안테나와 비교하여 97.2% 소형화 되었다. 또한 -10 dB 대역폭은 2.44 MHz(0.57%)로 측정되었으며 방사패턴은 E-plane $15^{\circ}$에서 최대 1.82 dBi의 이득을 얻었다.